As the cost of crude oils increases, in order to improve the profit for the refinery industry, heavy oils must be upgraded to meet demands. In upgrading, the heavier materials are converted to lighter fractions and most of the sulfur, nitrogen and metals must be removed. Crude oil is typically first processed in an atmospheric crude distillation tower to provide fuel products including naphtha, kerosene and diesel. The atmospheric crude distillation tower bottoms stream is typically taken to a vacuum distillation tower to obtain vacuum gas oil (VGO) that can be feedstock for an FCC unit or other uses. VGO typically boils in a range between at or about 300° C. (572° F.) and at or about 524° C. (975° F.).
Processing these heavier feeds results in increased amounts of the bottoms stream from the vacuum distillation tower, leading to increased amounts of less valuable products being produced.
Therefore, there is a need for processes and apparatus to increase the amount of valuable products such as petrochemicals (ethylene, propylene, aromatics) made from the heavier feeds and reduce the amount of less valuable products.